“[The issue with the merger is] all about CNN,” said one person with direct knowledge of the talks with the DoJ, adding that the regulator made it clear to AT&T that if it sold CNN the deal would go through.

Trump is opposed to the merger.

Mr Trump has not hidden his opposition to the deal, which had cleared regulatory hurdles in other countries and had been widely expected to be signed off by Washington. During the presidential campaign, Mr Trump had promised to reject the deal outright, saying it concentrated too much media control into a single corporate entity. The demands are “completely unreasonable” and “a complete perversion of the guidelines of the law”, one person with knowledge of the discussions said.